Google, the world's most popular internet search engine, has issued a legal warning to a rude copycat website - pornography-based Booble.

Bosses at Google are demanding that Booble, which allows users to search for adult products, changes its name and identity.

The Booble webpage, which was launched last week, currently looks very similar to that of Google's.

Booble insists it is merely a harmless parody.

Google, which according to press reports has delayed plans to float next week on the New York Stock Exchange, has issued a writ against Booble.

The legal document calls on the pornography site to "permanently refrain" from using Google's name or any variation on it "that is likely to cause confusion or dilution".

Joking aside

US-based Booble replied by asserting its right to parody under the first amendment.

"The entire universe gets the joke. Only a lawyer could say 'Booble' without smiling," it said.

Or apparently a senior Google executive. The search engine is refusing to accept that Booble is harmless mimicry.

"For a work to constitute a parody, it must use some elements of a prior author's composition to create a new one that, at least in part, comments on the original author's works," Google said in a formal reply to the pornography site.

Booble, which launched on 20 January, said it has proved so popular that the site has collapsed twice because of overuse.